1. Technical Field
The present invention relates to electrophoretic display devices with an electrophoretic (EPD) display function and contactless communication media provided with the electrophoretic display devices, and more particularly, to electrophoretic display devices and contactless communication media which are suitable for reducing the difficulty of the work at the time of designing them.
2. Related Art
Conventionally, an electrophoretic display device described in Japanese Patent 2612472 which is a display device using electrophoretic particles is known.
The electrophoretic display device described in Japanese Patent 2612472 concerns an electrophoretic display device having a structure in which a dispersion system having electrophoretic particles dispersed therein is divided into discontinuous phases through porous spacers and sealed between a pair of opposing electrode plates, at least one of which is formed to be transparent, and characterized in that one of the electrode plates is formed to be flexible so that it can be successively come in contact with the porous spacers, and the other electrode plate is formed from a transparent rigid member.
Also, Japanese Laid-open Patent Application 2000-322549 describes a contactless IC card as a contactless communication media equipped with a display device that uses electrophoretic particles.
The contactless IC card described in Japanese Laid-open Patent Application 2000-322549 has a structure in which an IC is provided on a substrate, and a working electrode for display, a counter electrode, power supply terminals for the IC and lead wires connecting these electrodes are formed on the substrate by screen printing. Then, a mixture of a high polymer electrolyte gel and an electrochromic material having a triphenylmethane structure which is a type of electrophoretic particles is formed in a film shape so as to cover the work electrode and the counter electrode to obtain a display element. The color of the display element is changed by a small voltage supplied from the IC to perform display. Even when the supply of the voltage is stopped, the display can be maintained for a long time.
However, both of the electrophoretic display device described in Japanese Patent 2612472 and the contactless IC card described in Japanese Laid-open Patent Application 2000-322549 compose a display section by directly containing electrophoretic particles and a dispersion medium or forming a film thereof between a pair of electrode plates. Therefore, a display pattern (one of electrodes) and a transparent electrode (the other electrode) are formed on one surface side of a substrate in either of the cases, such that time-consuming works, such as, laying out of numerous wiring patterns for applying voltages to the display pattern, positioning of transparent electrodes, and the like on one side of the substrate are necessary at the time of designing them. In particular, in the case of the contactless IC card of Japanese Laid-open Patent Application 2000-322549, the work required at the time of designing further increases because positioning of an antenna, a communication circuit and the like and laying out of wiring patterns required for them need to be conducted in addition of the display section.
Accordingly, the present invention has been made in view of the unsolved problems of the conventional technologies described above, and its object is to provide electrophoretic display devices and contactless communication media which are suitable for reducing the time and labor when designing them.
It is noted that, to solve the problems described above, the present inventor has made an invention in the past concerning Japanese Laid-open patent application 2003-390959, and the present applicant filed the application. The present invention pertains to another invention to solve the problems described above, in which a part of the previous invention is further advanced.